As semiconductor processing and, in particular, wafer processing has become automated, the work cell process station has evolved utilizing various process stations in conjunction with a robotic system. This allows various steps in the process to be performed in discrete steps. Generally, these process stations are aligned side by side and a wafer or similar workpiece is transferred from one process station to another by a robotic arm. The entire operation is carried out in a ventilated clean room environment.
One limitation that has been recognized with respect to the process stations, is that they have a predefined "foot print." Generally, there is a work surface which has a predefined area with a requirement for some type of functional equipment and support structure therebelow. The work surface receives a workpiece and is positioned to allow air to flow thereover. There is a working area above the work surface to allow the robotic arm to manipulate the workpiece. It is imperative that two closely spaced process stations not contaminate one another and, thus, there is a requirement that air passing over one work surface be directed down the side of the work surface and away from any adjacent work surfaces. Therefore, there is a region provided about the periphery of the work surface for allowing air flow therethrough.
In a ventilated clean room, a predefined air flow passes from above the work surface to the floor on which the process station is disposed. This air flow is normally filtered prior to passing over the work surface and then passing through an orifice of some sort in the floor of the clean room. This air is continually circulated and filtered It is important not to have any contaminants enter the air stream prior to the air contacting the work surface. This is to ensure that no particulate matter enters the air stream that could potentially contaminate the workpiece that is disposed on the work surface.
One disadvantage of present process stations is that they must be disposed side by side. This arrangement does not provide for efficient use of space or efficient use of the robot's range of motion. If the process stations are spaced at too great a distance, an additional robot may be necessary, which could result in inefficient use of the robot's time in that one robot may be idle for a given time during the processing of a given workpiece. In view of these disadvantages, it is desirable to provide a process station that more efficiently utilizes the process modules with respect to their ability to interface with the robot.